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The grass genera of the world

L. Watson, T.D. Macfarlane, and M.J. Dallwitz

Petriella Zotov

~ Ehrharta

Habit, vegetative morphology. Perennial; rhizomatous. Culms 1–40 cm high; woody and persistent, or herbaceous; unbranched above (but branching near the base). Culm nodes glabrous. Plants unarmed. Young shoots intravaginal. Leaves not basally aggregated; auriculate. Leaf blades linear-lanceolate to ovate-lanceolate; narrow; 2–3 mm wide; flat, or folded; not pseudopetiolate; without cross venation; disarticulating from the sheaths (from the lower sheaths), or persistent. Ligule a fringed membrane; not truncate; to 0.5 mm long. Contra-ligule absent.

Reproductive organization. Plants bisexual, all with bisexual spikelets; with hermaphrodite florets.

Inflorescence. Inflorescence a single raceme, or paniculate; contracted; espatheate; not comprising ‘partial inflorescences’ and foliar organs. Spikelet-bearing axes persistent. Spikelets solitary; not secund; pedicellate; imbricate.

Female-fertile spikelets. Spikelets 3–5 mm long; compressed laterally; disarticulating above the glumes; with conventional internode spacings. Rachilla terminated by a female-fertile floret. Callus absent.

Glumes present; two; more or less equal; shorter than the spikelets; shorter than the adjacent lemmas (2.0–3.5 mm long); hairless; glabrous; pointed, or not pointed; awnless; carinate; very dissimilar, or similar (G1 or G2 may be rounded, truncate or acute at the tip). Lower glume shorter than the lowest lemma; much shorter than half length of lowest lemma; 1–3 nerved. Upper glume 3–5 nerved. Spikelets with incomplete florets. The incomplete florets proximal to the female-fertile florets. Spikelets with proximal incomplete florets. The proximal incomplete florets 2 (the lemmas glabrous except at the base, without basal appendages, with prominent longitudinal veins but without transverse ribs); epaleate; sterile. The proximal lemmas awned (the apex acuminate, contracted into a short terminal awn); 0–7 nerved; more or less equalling the female-fertile lemmas to decidedly exceeding the female-fertile lemmas; decidedly firmer than the female-fertile lemmas; not becoming indurated.

Female-fertile florets 1. Lemmas decidedly firmer than the glumes (chartaceous); not becoming indurated; entire; blunt (truncate); awnless; hairless; glabrous; carinate; without a germination flap; 1–5 nerved. Palea present; relatively long (3/4 the length of the lemma); entire; awnless, without apical setae; thinner than the lemma (hyaline-membranous); not indurated; 1-nerved (i.e. the two veins contiguous); one-keeled. Lodicules present; 2; free; membranous; glabrous; at least slightly toothed; relatively heavily vascularized (cf. Ehrharta). Stamens 2. Anthers 1–1.5 mm long; without an apically prolonged connective. Ovary apically glabrous. Styles free to their bases. Stigmas 2; white.

Fruit, embryo and seedling. Fruit free from both lemma and palea; small (2–3.5 mm long); ellipsoid; strongly compressed laterally. Hilum long-linear. Embryo small.

Classification. Watson & Dallwitz (1994): Bambusoideae; Oryzodae; Ehrharteae. Soreng et al. (2015): cf. Oryzoideae (as a synonym?); Ehharteae. 2 species.

Distribution, phytogeography, ecology. New Zealand.

Helophytic to mesophytic; species of open habitats; glycophytic. Mountains.

Special comments. Seems scarcely distinguishable from Ehrharta and Tetrarrhena. Anatomical data wanting. Illustrations. • P. colensoi, as Ehrharta: Cheeseman (1914), Ill. New Zealand Flora, 2


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Cite this publication as: ‘Watson, L., Macfarlane, T.D., and Dallwitz, M.J. 1992 onwards. The grass genera of the world: descriptions, illustrations, identification, and information retrieval; including synonyms, morphology, anatomy, physiology, phytochemistry, cytology, classification, pathogens, world and local distribution, and references. Version: 13th November 2017. delta-intkey.com/grass’.

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